The invention relates to monitoring the processing of a substrate.
In substrate processing methods, features comprising semiconductor, dielectric, and conductor materials, including but not limited to, silicon, polysilicon, silicon dioxide, aluminum, copper and tungsten silicide materials, are formed on a substrate by, for example, chemical vapor deposition (CVD), physical vapor deposition (PVD), oxidation, nitridation, ion implantation, and etching processes. In CVD processes, a reactive gas is used to deposit material on the substrate. In PVD processes, a target is sputtered to deposit material on the substrate. In oxidation and nitridation processes, an oxide or nitride material, such as silicon dioxide or silicon nitride, is formed on the substrate by exposing the substrate to a suitable gaseous environment. In ion implantation, ions are implanted into the substrate, In conventional etching processes, etch-resistant features comprising resist or hard-mask, are formed on the substrate and the exposed portions of the substrate between the etch-resistant features (substrate open area) are etched to form patterns of gates, vias, contact holes or interconnect lines.
Conventional methods of monitoring the processing of a substrate or of a process conducted in a substrate processing chamber often have problems. The process monitoring methods may be used to stop or change the process, for example, after a pre-determined change occurs in a feature or material being processed, after a process stage, or at a process endpoint. For example, in the etching of trenches in a dielectric, such as silicon dioxide, on a silicon wafer, it may be desirable to stop etching after reaching a predetermined depth. In one conventional method, the time required to etch a particular depth in a substrate is calculated from a predetermined rate of etching and a starting thickness of the substrate layer or material being etched. In another method, the peaks resulting from the constructive and destructive interference of radiation reflected from the substrate are counted to determine a substrate etching depth. However, such techniques are often inaccurate when the starting thickness of the material on the substrate varies from one substrate to another or when other process parameters change. It is especially difficult to accurately monitor an etching process when the substrate being etched has a small open area between the etch-resistant features because the process signal from such a region is small relative to the process signal from other portions of the substrate. It is also difficult to determine the depth of a material deposited within a via or trench on the substrate, for example, during the deposition of dielectric or metal material into a via or trench, because of the small area of the deposited material.
Thus, it is desirable to detect a small change that may occur during processing of a substrate. It is also desirable to quantitatively evaluate the change, for example, a depth of etching, or a thickness of the material deposited upon, the substrate. It is further desirable to accurately monitor substrate processing during the etching of a substrate having small open areas or during the deposition of material into small areas on the substrate.
The present invention satisfies these needs. In one aspect, the present invention comprises a substrate processing apparatus comprising a chamber capable of processing a substrate, a radiation source to provide a radiation, a radiation polarizer adapted to polarize the radiation to one or more polarization angles that are selected in relation to an orientation of a feature being processed on the substrate, a radiation detector to detect radiation reflected from the substrate during processing and generate a signal, and a controller to process the signal.
In another aspect, the invention comprises a method of processing a substrate in a process zone, the method comprising the steps of providing a substrate in the process zone, setting process conditions to process the substrate with an energized gas, providing radiation that is polarized at one or more polarization angles that are selected in relation to an orientation of a feature being processed on the substrate, detecting radiation reflected from the substrate and generating a signal in response to the detected radiation, and processing the signal.
In yet another aspect, the invention comprises a substrate processing apparatus comprising a chamber capable of processing a substrate, a radiation source to provide a radiation, a radiation polarizer adapted to polarize the radiation to a plurality of polarization angles, a radiation detector to detect radiation reflected from the substrate during processing and generate a signal, and a controller to process the signal.
In a further aspect, the invention comprises a method of processing a substrate in a process zone, the method comprising the steps of providing a substrate in the process zone, setting process conditions to process a feature on the substrate with an energized gas, providing radiation that is polarized to a plurality of polarization angles, detecting radiation reflected from the substrate and generating a signal in response to the detected radiation, and processing the signal.
In another aspect, the invention comprises a substrate processing apparatus comprising a chamber capable of processing a substrate, a radiation source to provide a radiation, a radiation detector to detect radiation reflected from the substrate during processing and generate a signal, and a bandpass filter to filter the signal.
In another aspect, the invention comprises a substrate processing method comprising placing a substrate in a process zone, setting process conditions of an energized gas to process the substrate, providing a source of radiation in the process zone, detecting radiation that is reflected from a substrate during processing of the substrate and generating a signal, and filtering the signal.
In another aspect, the present invention comprises a substrate processing apparatus comprising a process chamber comprising a substrate support, gas inlet, gas energizer, gas exhaust, and a wall having a recess with a window therein and a mask over the window, and a process monitoring system capable of monitoring a process that may be conducted in the process chamber, through the window in the recess of the wall.
In a further aspect, the present invention comprises a method of processing a substrate in a chamber, the method comprising, placing the substrate in the chamber, providing an energized gas in the chamber to process the substrate, masking a window provided in a recess in a wall of the chamber, and monitoring a process that may be conducted in the chamber through the window in the recess in the wall.